​Next.js - Framework for server-rendered or statically-exported React apps.
​San - Flexible JavaScript component framework.
​hapi - Rich framework for building applications and services.
​Koa - Smaller, more expressive, and more robust foundation for web applications and APIs.
​Umi - Pluggable enterprise-level react application framework.
​Vue.js - Progressive JavaScript Framework.
​Mithril - Modern client-side Javascript framework for building Single Page Applications. (HN)
​Solid - Declarative, efficient, and flexible JavaScript library for building user interfaces.
​Neutrino dev​
​Alpine.js - Rugged, minimal framework for composing JavaScript behavior in your markup. (Awesome Alpine)
​After.js - Next.js-like framework for server-rendered React apps built with React Router 4.
​Torus - Event-driven model-view UI framework for the web, focused on being tiny, efficient, and free of dependencies. (Web)
​Hyperapp - Tiny framework for building web interfaces. (Web) (HN) (Hyperawesome)
​Hyperapp FX - Effects for use with Hyperapp.
​Phenomic - Modular website compiler (React, Webpack, Reason and whatever you want).
​Halfmoon - Front-end framework with a built-in dark mode and full customizability using CSS variables; great for building dashboards and tools. (Docs)
​Sinuous - Low-level UI library with a tiny footprint. (Docs)
​Overture - Powerful JS library for building really slick web applications, with performance at, or surpassing, native apps.
​Lucia - Tiny library for tiny web apps. (Docs)
​Ractive.js - Next-generation DOM manipulation.
​JSX Lite - Write components once, run everywhere. Compiles to Vue, React, Solid, Liquid, and more.
​Perlite - Hyperactiv + lit-html + extensions. Simple and declarative way to create rich client-side widgets designed with server-side apps in mind.
​Democrat - Library that mimic the API of React (Components, hooks, Context...) but instead of producing DOM mutation it produces a state tree.
​Raj - Elm Architecture for JavaScript.
​Reframe - New kind of web framework.
​observablehq/stdlib - Observable standard library.
​Choo - Sturdy 4kb frontend framework. (Web)
​Typera - Type-safe routes for Express and Koa.
​Frourio - Fast and type-safe full stack framework, for TypeScript. (Web)
​Svelto - Modular front end framework for modern browsers, with battery included: 100+ widgets and tools.
​modular - Collection of tools and guidance to enable UI development at scale. (Tweet)
​Turbo - Speed of a single-page web application without having to write any JavaScript. (Web)
​Fre - Tiny Coroutine framework with Fiber.
​Glimmer - Fast and light-weight UI components for the web. (Code)
​Glimmer VM - Flexible, low-level rendering pipeline for building a "live" DOM from Handlebars templates that can subsequently be updated cheaply when data changes.
​frint - Modular JavaScript framework for building scalable and reactive applications.
​Nano Router - Framework agnostic minimalistic router with a focus on named routes.
​tiny-request-router - Fast, generic and type safe router (match request method and path).
​Synergy - Tiny runtime library for building web user interfaces. (HN)
​dflex - JavaScript Project to Manipulate DOM Elements.
​morphdom - Fast and lightweight DOM diffing/patching (no virtual DOM needed).
​Forgo - Ultra-light UI runtime. Makes it super easy to create modern web apps using JSX (like React).
​Whats Up - Front-end framework based on ideas of streams and fractals.
​Boost - Collection of type-safe cross-platform packages for building robust server-side and client-side systems.
​Nostalgie - Opinionated, full-stack, runtime-agnostic framework for building web apps and web pages using react. (Web)
​Lumino - Library for building interactive web applications.

​Anime.js - JavaScript animation engine.
​popmotion - Functional, reactive animation library.
​impress.js - Presentation framework based on the power of CSS3 transforms and transitions.
​Pts - Library for visualization and creative-coding.
​lax.js - Simple & light weight (<2kb gzipped) vanilla JS plugin to create smooth & beautiful animations when you scroll.
​Flipping - Library (and collection of adapters) for implementing FLIP transitions.
​Ola - Smooth animation library for interpolating numbers.
​react-spring - Spring physics based React animation library.
​FAT - Web's fastest and most lightweight animation tool.
​React Easy Flip - Lightweight React library for smooth FLIP animations.
​AOS - Animate on scroll library.
​flubber - Tools for smoother shape animations.

​qoa - Minimal interactive command-line prompts.

​Unexpected - Extensible BDD assertion toolkit. (Docs)
​Fishery - Library for setting up JavaScript objects as test data.
​pentf - Parallel end-to-end test framework.
​test-flat - Test framework extension to support resources teardown and cleanup in flat tests.
​zora - Lightest, yet Fastest JavaScript test runner for nodejs and browsers.
​Vest - Declarative Validation Testing.

​Mutik - Tiny (495B) immutable state management library based on Immer.
​Overmind - Frictionless state management. (Docs) (HN)
​Storeon - Tiny event-based Redux-like state manager for React and Preact.
​Overstated - React state management library that's delightful to use, without sacrificing performance or scalability.
​Effector - Reactive state manager. (Awesome) (Docs) (effector-storage)
​Akita - State Management Tailored-Made for JS Applications.
​Observable Store - Provides a simple way to manage state in Angular, React, Vue.js and other front-end applications.
​Cerebral - Declarative state and side effects management solution for popular JavaScript frameworks.
​Hooksy - State management solution based on react hooks.
​React Easy State - Simple React state management. Made with ❤️ and ES6 Proxies.
​wana - Easy observable state for React.
​Recoil - Experimental set of utilities for state management with React. (Web) (Video) (Reddit) (Rewriting from scratch) (Recoilize - Recoil developer tool)
​State Designer - JavaScript and TypeScript library for managing the state of a user interface.
​Fluxible - Pluggable container for universal flux applications.
​Logux State - Tiny state manager with CRDT, cross-tab, and Logux support.
​Statery - Surprise-Free State Management. Designed for React with functional components.

​NodeJS Instagram private API client​

​sql.js - SQLite compiled to JavaScript. Allows you to create a relational database and query it entirely in the browser. (Docs) (HN)
​SQigiL - Postgres SQL template string for Javascript.
​Postgrest JS - Isomorphic JavaScript client for PostgREST.
​Connect PG Simple - Simple, minimal PostgreSQL session store for Express/Connect.

​state-machines-in-react - Small React, xstate and Framer Motion demo.

​micro github - Tiny microservice that makes adding authentication with GitHub to your application easy.
​pico.js - Face detection library in 200 lines of JavaScript.
​mdxc - Use React Components within Markdown.
​ReLaXeD - Create PDF documents using web technologies. (Examples)
​Dragula - Drag and drop so simple it hurts.
​Hammer.js - Multi-touch gestures.
​emittery - Simple and modern async event emitter.
​Xstate - State machines and statecharts for the modern web. (State Machines Workshop)
​xstate-component-tree - Build a tree of UI components based on your state chart.
​virtual-scroller - Maps a provided set of JavaScript objects onto DOM nodes, and renders only the DOM nodes that are currently visible, leaving the rest "virtualized".
​jSPDF - Client-side JavaScript PDF generation for everyone.
​ForgJS - JavaScript lightweight object validator.
​faker.js - Generate massive amounts of realistic fake data in Node.js and the browser.
​arg - Simple argument parsing.
​fbt - JavaScript Internationalization Framework.
​fuzzysearch - Tiny and blazing-fast fuzzy search in JavaScript.
​normalizr - Normalizes nested JSON according to a schema.
​FBJS - Collection of utility libraries used by other Facebook JS projects.
​Uppy - Next open source file uploader for web browsers. (Web)
​ScrollReveal - Animate elements as they scroll into view.
​Shiny - Add shiny reflections to text, backgrounds, and borders on devices that support the DeviceMotion event.
​Hotkey Behavior - Trigger a action on element when keyboard hotkey is pressed.
​Bili - Makes it easier to bundle JavaScript libraries.
​Memoizee - Complete memoize/cache solution for JavaScript.
​Immer - Create the next immutable state by mutating the current one.
​FlexSearch - Web's fastest and most memory-flexible full-text search library with zero dependencies.
​cofx - Node and javascript library that helps developers describe side-effects as data in a declarative, flexible API.
​Mercury Parser - Extracts the bits that humans care about from any URL you give it.
​Refract - Harness the power of reactive programming to supercharge your components.
​MemJS - Memcache client for node using the binary protocol and SASL authentication.
​memfs - In-memory filesystem with Node's API.
​Accounts - Fullstack authentication and accounts-management for GraphQL and REST.
​Cleave.js - Format input text content when you are typing...
​Unistore - Tiny 350b centralized state container with component bindings for Preact & React.
​Ramda - Practical functional library for JavaScript programmers.
​fromfrom - JS library written in TS to transform sequences of data from format to another.
​Editor.js - Block-styled editor with clean JSON output.
​ijk - Transforms arrays into virtual DOM trees.
​Cleave.js - Format input text content when you are typing.
​Oboe.js - Streaming approach to JSON. Oboe.js speeds up web applications by providing parsed objects before the response completes.
​Choices.js - Vanilla JS customisable select box/text input plugin.
​Shepherd - Guide your users through a tour of your app.
​object-cull - Create a copy of an object with just the bits you actually need.
​Sigma - JavaScript library dedicated to graph drawing.
​interact.js - JavaScript drag and drop, resizing and multi-touch gestures with inertia and snapping for modern browsers.
​flru - Tiny (215B) and fast Least Recently Used (LRU) cache.
​Yup - Dead simple Object schema validation.
​Lerna - Tool for managing JavaScript projects with multiple packages.
​WikiJs - Wikipedia Interface for Node.js.
​virtual-audio-graph - Library for declaratively manipulating the Web Audio API.
​deep-object-diff - Deep diffs two objects, including nested structures of arrays and objects, and returns the difference.
​Snarkdown - Snarky 1kb Markdown parser written in JavaScript.
​Terser - JavaScript parser, mangler, optimizer and beautifier toolkit for ES6+.
​AppAuthJS - JavaScript client SDK for communicating with OAuth 2.0 and OpenID Connect providers.
​expr-eval - Mathematical expression evaluator in JavaScript.
​robust-predicates - Fast robust predicates for computational geometry in JavaScript.
​Sanctuary - JavaScript functional programming library inspired by Haskell and PureScript.
​modali - Delightful modal dialog component for React, built from the ground up to support React Hooks.
​Tweakpane - Compact GUI for fine-tuning parameters and monitoring value changes.
​crocks - Collection of well known Algebraic Data Types for your utter enjoyment.
​Just - Library of zero-dependency npm modules that do just do one thing.
​nanoid - Tiny (139 bytes), secure, URL-friendly, unique string ID generator for JavaScript.
​debug - Tiny JavaScript debugging utility modelled after Node.js core's debugging technique. Works in Node.js and web browsers.
​roughViz.js - Reusable JavaScript library for creating sketchy/hand-drawn styled charts in the browser.
​Mitt - Tiny 200 byte functional event emitter / pubsub.
​RequireJS - File and module loader for JavaScript.
​Zero - 3D graphics rendering pipeline. Implemented in JavaScript. Run in a terminal.
​xstate-viz - Visualize state charts.
​htmr - Simple and lightweight (< 2kB) HTML string to React element conversion library.
​react-jsx-parser - React component which can parse JSX and output rendered React Components.
​Static Land - Specification for common algebraic structures in JavaScript based on Fantasy Land.
​sorted-queue - Sorted queue, based on an array-backed binary heap.
​polendina - Non-UI browser testing for JavaScript libraries from the command-line.
​agadoo - Check whether a package is tree-shakeable.
​Fielder - React form library which adapts to change.
​lemonad - Functional programming library for JavaScript. An experiment in elegant JS.
​Mockttp - Lets you quickly & reliably test HTTP requests & responses in JavaScript, in both Node and browsers.
​Flowy - Minimal javascript library to create flowcharts.
​d3-dag - Layout algorithms for visualizing directed acyclic graphs.
​renature - Physics-based animation library for React focused on modeling natural world forces.
​Morphism - Do not repeat anymore your objects transformations.
​Tonic - Stable, Minimal, Auditable, Build-Tool-Free, Low Profile Component Framework.
​Quiet.js - Transmit data with sound using Web Audio -- Javascript binding for libquiet.
​Bindery - Library for designing printable books with HTML and CSS.
​Wretch - Tiny wrapper built around fetch with an intuitive syntax.
​Virt.js - Free collection of useful standard devices, that can be used to power various engine that makes use of the exposed interfaces.
​Path-to-RegExp - Turn a path string such as /user/:name into a regular expression.
​Bacon.js - Functional reactive programming library for TypeScript and JavaScript.
​GGEditor - Visual graph editor based on G6 and React.
​Arbor - Graph visualization library using web workers and jQuery. (Web)
​fsm-as-promised - Finite state machine library using ES6 promises.
​x-spreadsheet - Web-based JavaScript（canvas）spreadsheet.
​IsoCity - Isometric city builder in JavaScript.
​car - Simple 2d car physics with JavaScript. (HN)
​Picomatch - Blazing fast and accurate glob matcher written in JavaScript.
​react-isomorphic-data - Easily fetch data in your React components, with similar APIs to react-apollo.
​klona - Tiny (228B) and fast utility to "deep clone" Objects, Arrays, Dates, RegExps, and more.
​ScrollMagic - JavaScript library for magical scroll interactions.
​GoJS - JavaScript and TypeScript library for building interactive diagrams and graphs.
​Rete - JavaScript framework for visual programming and creating node editor. (HN)
​Pre3d - JavaScript 3d rendering engine.
​dancer.js - High-level audio API, designed to make sweet visualizations.
​model-viewer - Easily display interactive 3D models on the web and in AR.
​Spars - General toolkit for creating interactive web experiences.
​NeuroJS - JavaScript deep learning and reinforcement learning library.
​Hareactive - Purely functional reactive programming library.
​Mirage JS - Client-side server to develop, test and prototype your JavaScript app.
​dfa - State machine compiler with regular expression style syntax.
​Jtree - Tree Notation TypeScript/Javascript library.
​Hydra - Livecoding networked visuals in the browser.
​p-queue - Promise queue with concurrency control.
​gsheets - Get public Google Sheets as plain JavaScript/JSON.
​alga-ts - Algebraic graphs implementation in TypeScript.
​Chart.js - Simple HTML5 Charts using the tag. (Awesome)
​on-change - Watch an object or array for changes.
​clean-set - Deep assignment alternative to the object spread operator and Object.assign.
​Search Query Syntax Parser​
​Uppload - Better JavaScript image uploader with 30+ plugins.
​pino - Super fast, all natural JSON logger.
​Orbit - Composable data framework for ambitious web applications.
​panzoom - Universal pan and zoom library (DOM, SVG, Custom).
​intl-tel-input - JavaScript plugin for entering and validating international telephone numbers.
​three.js - JavaScript 3D library.
​shortid - Short id generator. Url-friendly. Non-predictable. Cluster-compatible.
​styx - Derives a control flow graph from a JavaScript AST.
​Crossfilter - JavaScript library for exploring large multivariate datasets in the browser.
​SiriWave - Apple Siri wave-form replicated in a JS library.
​Shades - Lodash-inspired lens-like library for Javascript.
​mxGraph - Fully client side JavaScript diagramming library.
​cacache - Node.js library for managing local key and content address caches.
​enhanced-resolve - Offers an async require.resolve function. It's highly configurable.
​notevil - Evalulate javascript like the built-in javascript eval() method but safely.
​react-digraph - Library for creating directed graph editors.
​bent - Functional JS HTTP client (Node.js & Fetch) w/ async await.
​CLUI - Collection of JavaScript libraries for building command-line interfaces with context-aware autocomplete.
​cosha - Colorful shadows for your images.
​Rambda - Faster and smaller alternative to Ramda.
​MathJax - Open-source JavaScript display engine for LaTeX, MathML, and AsciiMath notation that works in all modern browsers. (Web) (HN)
​Litepicker - Date range picker - lightweight, no dependencies.
​core-js - Modular standard library for JavaScript.
​timeago.js - Nano library (less than 2 kb) used to format datetime with *** time ago statement. eg: '3 hours ago'.
​Serialize JavaScript - Serialize JavaScript to a superset of JSON that includes regular expressions, dates and functions.
​Tippy.js - Tooltip, popover, dropdown, and menu library.
​howler.js - JavaScript audio library for the modern web.
​date-fns - Modern JavaScript date utility library.
​Midi - Convert MIDI into Tone.js-friendly JSON.
​face-api.js - JavaScript API for face detection and face recognition in the browser and nodejs with tensorflow.js.
​Spotlight - Search widget for your web API.
​Fuse - Lightweight fuzzy-search, in JavaScript.
​Xterm.js - Terminal for the web.
​Change Case - Convert strings between camelCase, PascalCase, Capital Case, snake_case and more.
​ChronoGraph - Reactive, graph-based, computation engine.
​Sprotty - Diagramming framework for the web.
​prerender.js - Loads pages quickly on any browser.
​on-finished - Execute a callback when a request closes, finishes, or errors.
​ColorFns - Modern JavaScript color utilities library.
​grapheme-splitter - JavaScript library that breaks strings into their individual user-perceived characters.
​Web Animations - JavaScript implementation of the Web Animations API.
​p-limit - Run multiple promise-returning & async functions with limited concurrency.
​Highcharts JS - JavaScript charting library based on SVG.
​μPlot - Small, fast chart for time series, lines, areas, ohlc & bars.
​Baobab - JavaScript & TypeScript persistent and optionally immutable data tree with cursors.
​emoji-regex - Regular expression to match all Emoji-only symbols as per the Unicode Standard.
​MerkleTree.js - Construct Merkle Trees and verify proofs in JavaScript.
​Snabbdom - Virtual DOM library with focus on simplicity, modularity, powerful features and performance.
​Thwack - Tiny modern data fetching solution.
​Regenerate - Generate JavaScript-compatible regular expressions based on a given set of Unicode symbols or code points.
​Crank.js - Write JSX-driven components with functions, promises and generators. (Article) (Reddit) (HN)
​redaxios - Axios API, as an 800 byte Fetch wrapper.
​Math.js - Extensive math library for JavaScript and Node.js.
​pixelmatch - Smallest, simplest and fastest JavaScript pixel-level image comparison library.
​quilt - Loosely related set of packages for JavaScript / TypeScript projects at Shopify.
​jsondiffpatch - Diff & patch JavaScript objects.
​RVal - Minimalistic transparent reactive programming library.
​orbit-controls - Generic controls for orbiting a target in 3D.
​estree-walker - Traverse an ESTree-compliant AST.
​Jitsi Meet API library - Can use Jitsi Meet API to create Jitsi Meet video conferences with a custom GUI.
​isomer - Simple isometric graphics library for HTML5 canvas.
​Schema to Yup schema​
​Mordred - Source data from anywhere, for Next.js, Nuxt.js, Eleventy and many more.
​ASScroll - Hybrid smooth scroll setup that combines the performance gains of virtual scroll with the reliability of native scroll.
​Gallery - Light, responsive, and performant JavaScript gallery.
​Logux Server - Build own Logux server or make proxy between WebSocket and HTTP backend on any language.
​@expo/results - Efficient, standards-compliant library for representing results of successful or failed operations.
​Emojibase - Collection of lightweight, up-to-date, pre-generated, specification compliant, localized emoji JSON datasets, regex patterns, and more.
​serve-favicon - Node.js middleware for serving a favicon.
​download - Download and extract files.
​color2k - Color parsing and manipulation lib served in 2kB or less.
​Sandstorm - Open source platform for self-hosting web apps. (Code)
​transformation-matrix - JS isomorphic 2D affine transformations written in ES6 syntax.
​Muuri - JavaScript layout engine that allows you to build all kinds of layouts and make them responsive, sortable, filterable, draggable and/or animated.
​Split - Unopinionated utilities for resizeable split views.
​Parallax Engine - Reacts to the orientation of a smart device.
​fastq - Fast, in memory work queue.
​ac-colors - Reactive JavaScript color library that can freely convert color formats.
​sonic-boom - Extremely fast utf8 only stream implementation.
​Rough Notation - Small JavaScript library to create and animate annotations on a web page. (HN)
​SqueakJS - Squeak VM for the Web and Node.js. (Web)
​fit-textarea - Automatically expand a to fit its content, in a few bytes.
​NanoPop - Ultra Tiny, Opinionated Positioning Engine. (Web)
​Angelfire - Lets you quickly build right-click-enabled context menus and drop-down menus for any element on your webpage.
​csv-parser - Streaming csv parser inspired by binary-csv that aims to be faster than everyone else.
​updeep - Easily update nested frozen objects and arrays in a declarative and immutable manner.
​Hull.js - JavaScript library that builds concave hull by set of points.
​StegCloak - Hide secrets with invisible characters in plain text securely using passwords.
​p-min-delay - Delay a promise a minimum amount of time.
​match-when - Pattern matching for modern JavaScript.
​NumJs - Like NumPy, in JavaScript.
​spect - Reactive aspect-oriented web-framework.
​js-cid - CID implementation in JavaScript.
​js-ipld-block - Implementation of the Block data structure in JavaScript.
​wildcard-api - Functions as API.
​bpmn-js - BPMN 2.0 rendering toolkit and web modeler.
​fit-curve - JavaScript implementation of Philip J. Schneider's "Algorithm for Automatically Fitting Digitized Curves" from the book "Graphics Gems".
​clean-deep - Remove falsy, empty or nullable values from objects.
​regular-table - Regular library, for async and virtual data models.
​Stimulus - Modest JavaScript framework for the HTML you already have. (Web)
​bigpicture.js - Library that allows infinite panning and infinite zooming in HTML pages. (Web)
​Tragopan - Minimal dependency-free pan/zoom library. (HN)
​Deakins - Small Canvas 2D Camera.
​Turbolinks - Makes navigating your web application faster.
​CindyJS - Framework to create interactive (mathematical) content for the web. (Web) (HN)
​axios - Promise based HTTP client for the browser and nodeJS.
​astray - Walk an AST without being led astray.
​vnopts - Validate and normalize options.
​canvas confetti - On-demand confetti gun. (Docs)
​Graphlib - JavaScript library that provides data structures for undirected and directed multi-graphs along with algorithms that can be used with them.
​Dagre - JavaScript library that makes it easy to lay out directed graphs on the client-side.
​ecsy - Highly experimental Entity Component System framework implemented in javascript, aiming to be lightweight, easy to use and with good performance. (Docs)
​Object Visualizer - Visualize the JSON object to the DOM. (HN)
​Reach Schema - Functional schema-driven JavaScript object validation library.
​@cycle/callbags - Set of commonly used stream operators implemented as callbags with Typescript and ES modules.
​umbrella - Broadly scoped ecosystem & mono-repository of ~135 TypeScript projects for functional, data driven development.
​HTM - JSX-like syntax in plain JavaScript - no transpiler necessary.
​NativeScript - Framework for building native iOS and Android apps using JavaScript and CSS.
​schema-dts - JSON-LD TypeScript types for Schema.org vocabulary.
​flatpickr - JS date time picker.
​superjson - Safely serialize JavaScript expressions to a superset of JSON, which includes Dates, BigInts, and more.
​lazy-collections - Collection of fast and lazy operations.
​Perfect Arrows - Set of functions for drawing perfect arrows between points and shapes.
​Autocomplete.js - Fast and full-featured autocomplete library.
​urlcat - URL builder library for JavaScript. (Docs)
​Diagram Maker - Library to display an interactive editor for any graph-like data. (Docs) (HN)
​js-coroutines - 60fps with JavaScript Coroutines for idle processing and animation.
​Transducist - Ergonomic JavaScript/TypeScript transducers for beginners and experts.
​decimal.js - Arbitrary-precision Decimal type for JavaScript.
​Constant-Time JavaScript - Constant-time algorithms written in TypeScript.
​SheetJS - Spreadsheet Data Toolkit. Read, edit, and export spreadsheets. Works in web browsers and servers. (Web)
​Z - Pattern Matching for JavaScript. (Web)
​Graphology - Robust & multipurpose Graph object for JavaScript & TypeScript. (Docs)
​weak-napi - Make weak references to JavaScript Objects.
​nestie - Tiny (211B) and fast utility to expand a flattened object.
​Mock.js - Simulation data generator.
​Detect features - Detect and report browser and hardware features.
​JSZip - Create, read and edit .zip files with JavaScript.
​Classnames - Simple javascript utility for conditionally joining classNames together.
​cx - Concatenate your classes (with shortcuts).
​Defer - Tiny, type-safe, JavaScript-native defer implementation.
​freshie - Fresh take on building universal applications with support for pluggable frontends and backends.
​Luckysheet - Online spreadsheet like excel that is powerful, simple to configure, and completely open source. (Docs)
​noUiSlider - Lightweight JavaScript range slider.
​QRCode.js - Cross-browser QRCode generator for JavaScript. (Web)
​HyperScript - Create HyperText with JavaScript, on client or server.
​hyperscript-helpers - Terse syntax for hyperscript.
​EnlighterJS - Open source syntax highlighter written in pure javascript.
​eslisp - S-expression syntax for JavaScript, with Lisp-like hygienic macros. Minimal core, maximally customisable.
​Smoldash - Tiny lodash alternative built for the modern web.
​TypewriterJS - Simple yet powerful native javascript plugin for a cool typewriter effect.
​sse.js - Flexible Server Side Events source for JavaScript.
​Arkit - Visualises JavaScript, TypeScript and Flow codebases as meaningful and committable architecture diagrams. (Web)
​jsii - Allows code in any language to naturally interact with JavaScript classes.
​proxy-memoize - Intuitive magical memoization library with Proxy and WeakMap. (Tweet)
​CosmJS - Modular library consisting of multiple packages to power web experiences.
​Arwes - Futuristic Sci-Fi and Cyberpunk Graphical User Interface Framework for Web Apps. (Web)
​psl (Public Suffix List) - JavaScript domain name parser based on the Public Suffix List.
​invariant-packages - Packages for working with invariant(condition, message) assertions.
​evt - EventEmitter's typesafe replacement.
​webscan - Browser-based network scanner & local-IP detection.
​Pill - Add dynamic content loading to static sites with only 1 KiB of JS.
​fast-deep-equal - Fastest deep equal with ES6 Map, Set and Typed arrays support.
​preview-card - Customizable social media preview image.
​egjs-flicking - Easy-to-use and performant infinite carousel.
​SSE-Z - Slim, easy-to-use wrapper around EventSource.
​DefinitelyExported - Community-defined export maps for popular npm packages.
​jsdiff - JavaScript text differencing implementation.
​HyperFormula - Open source, spreadsheet-like calculation engine.
​fast-json-stringify - Significantly faster than JSON.stringify() for small payloads.
​isbot - JavaScript module that detects bots/crawlers/spiders via the user agent.
​valtio - Makes proxy-state simple.
​pica - High quality image resize in browser.
​Planton - Database-agnostic task scheduler.
​mime-types - JavaScript content-type utility.
​match-sorter - Simple, expected, and deterministic best-match sorting of an array in JavaScript.
​Fetch Event Source - Better API for making Event Source requests, with all the features of fetch().
​rafz - Coordinate requestAnimationFrame calls across your app and/or libraries.
​p-state - Inspect the state of a promise.
​v86 - x86 virtualization in JavaScript, running in your browser and NodeJS. (Web)
​Notyf - Minimalistic, responsive, vanilla JavaScript library to show toast notifications.
​Moveable - Draggable, Resizable, Scalable, Rotatable, Warpable, Pinchable, Groupable, Snappable.
​Execa - Process execution for humans.
​quick-lru - Simple “Least Recently Used” (LRU) cache.
​Deepdash - Tree traversal library written in Underscore/Lodash fashion. (Docs)
​Nano Delay - Tiny (25 bytes) Promise wrapper around setTimeout.
​ES Module Lexer - Low-overhead lexer dedicated to ES module parsing for fast analysis.
​keez - Frictionless hotkey handling for browsers.
​Zet - Set() as it should be.
​Ketting - Hypermedia client for JavaScript.
​yocto-queue - Tiny queue data structure.
​Nano JSX - Lightweight 1kB JSX library. (Web)
​Effects.js - Algebraic effects in javascript with scoped handlers, multishot delimited continuations, stack safety and do notation.
​flatten-js - JavaScript library for 2d geometry.
​is-retry-allowed - Check whether a request can be retried based on the error.code.
​backfill - JavaScript caching library for reducing build time.
​S-Libs - Collection of libraries for any of JS, RxJS, or Angular.
​watchpack - Wrapper library for directory and file watching.
​async-tag - Resolves template literals tag values before applying a generic tag.
​serialize-error - Serialize/deserialize an error into a plain object.
​errorstacks - Tiny library to parse error stack traces.
​Ape-ECS - Entity-Component-System library for JavaScript.
​rrule.js - JavaScript library for working with recurrence rules for calendar dates as defined in the iCalendar RFC and more. (Demo)
​scroller - Super-tiny library for your scrollytelling needs.
​Isomorphic DOMPurify - Makes it possible to use DOMPurify on server and client in the same way.
​navaid - Navigation aid (aka, router) for the browser in 850 bytes.
​glob-to-regexp - Convert a glob to a regular expression.
​cmap - Interactive visualization library for concept map.
​lezer-tree - Incremental GLR parser intended for use in an editor or similar system.
​matchit - Quickly parse & match URLs.
​acorn - Tiny, fast JavaScript parser, written completely in JavaScript.
​jsesc - Given some data, jsesc returns the shortest possible stringified & ASCII-safe representation of that data.
​fastjson - Single-tweet, standards-compliant, high-performance JSON stack.
​grfn - Tiny (~400B) utility that executes a dependency graph of async functions as concurrently as possible.
​Nunjucks - Powerful templating engine with inheritance, asynchronous control, and more. (Web)
​Behavior3JS - Structures and algorithms that assist you in the task of creating intelligent agents for your game or application.
​qs - Querystring parser with nesting support.
​Exifer - Small module that read JPEG/TIFF meta-data.
​jsVideoUrlParser - JavaScript parser to extract information like provider, channel, id, start time from YouTube, Vimeo, Dailymotion, Twitch,... urls.
​TypeDI - Dependency injection tool for TypeScript and JavaScript.
​ibridge - Tiny, promise based, type safe library for easy, bidirectional and secure iframe communication.
​Monio - Async-capable IO monad for JS.
​Total.js - Excellent and stable server-side Node.js framework, client-side library for creating web applications with more than 230 UI components for free.
​memoize-one - Memoization library which only remembers the latest invocation.
​pjson - JSON stream parser for Go.
​InternMap - Map and Set with automatic key interning.
​geometry-processing-js - Fast, general-purpose framework for geometry processing on the web.
​Iterplus - Best of Rust/Haskell/Python iterators in JavaScript.
​SmolScroll - Tiny, flexible scroll listener with React support.
​Observable parser​
​Robot - Functional, immutable Finite State Machine library. (Docs)
​Enmap - Enhanced Map structure with additional utility methods.
​Honeycomb - Create hex grids easily, in node or the browser.
​chunkify - Split an iterable into evenly sized chunks.
​wobble - Tiny spring physics micro-library that models a damped harmonic oscillator.
​tmp-cache - Least-recently-used cache in 35 lines of code.
​static-eval - Evaluate statically-analyzable expressions.
​Sparse Octree - Sparse, pointer-based octree data structure.
​Signature Pad - JavaScript library for drawing smooth signatures.
​dom-to-image-retina - dom-to-image but generates high-resolution images.
​loglevel - Minimal lightweight logging for JavaScript, adding reliable log level methods to wrap any available console.log methods.
​Perfect Freehand - Draw perfect freehand lines.
​Alo - Full-fledged state management. (Docs)
​Form-Data - Library to create readable "multipart/form-data" streams. Can be used to submit forms and file uploads to other web applications.
​conf - Simple config handling for your app or module.
​gifenc - Fast and lightweight pure-JavaScript GIF encoder.
​tldts - Blazing Fast URL Parsing.
​Barba.js - Easy-to-use library that helps you create fluid and smooth transitions between your website's pages.
​Shuffle.js - Categorize, sort, and filter a responsive grid of items. (Web)
​stdlib - Standard library for JavaScript and Node.js. (Web)
​gensync - Allows users to use generators in order to write common functions that can be both sync or async.
​monet.js - Monadic types library for JavaScript.
​VivaGraph - Graph drawing library for JavaScript.
​Crochet - Small engine for story-driven games.
​diary - Zero-dependency, fast logging library for both Node and Browser.
​tinydate - Tiny reusable date formatter.
​FingerprintJS - Browser fingerprinting library with the highest accuracy and stability.
​Antiutils - TypeScript/JavaScript utilities for those who don't like utilities.

​NPM - Node package manager registry.
​Awesome WebAudio​
​Awesome XState​
​Moiva.io - Measure and compare JavaScript libraries side by side.
​Scarf - Installation analytics for your npm package. (Code)